title: Scanning electron microscopy of individual nanoparticle bio-markers in liquid.
abstract: We investigated SEM imaging of nanoparticle biomarkers suspended below a thin membrane, with the ultimate goal of integrating functional fluorescence and structural SEM measurements of samples kept at ambient or hydrated conditions. In particular, we investigated how resolving power in liquid SEM is affected by the interaction of the electron beam with the membrane. Simulations with the Geant4-based Monte Carlo scheme developed by Kieft and Bosch (2008) [1] are compared to experimental results with suspended nanoparticles. For 20 nm and 50 nm thin membranes, we found a beam broadening of 1.5 nm and 3 nm, respectively, with an excellent agreement between simulations and experiments. 15 nm Au nanoparticles and bio-functionalized core-shell quantum dots can be individually resolved in denser clusters. We demonstrated the imaging of single EGF-conjugated quantum dots docked at filopodia during cellular uptake with both fluorescence microscopy and SEM simultaneously. These results open novel opportunities for correlating live fluorescence microscopy with structural electron microscopy.
authors.affiliation: Department of Imaging Science & Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. Electronic address: n.liv@tudelft.nl.
authors.forename: Nalan
authors.initials: N
authors.lastname: Liv
authors.affiliation: Department of Imaging Science & Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors.forename: Ivan
authors.initials: I
authors.lastname: Lazić
authors.affiliation: Department of Imaging Science & Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Kruit
authors.affiliation: Department of Imaging Science & Technology, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Hoogenboom
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000737:chemistry*; D002460:Cell Line; D004583:Electrons; D005347:Fibroblasts / Q000166:cytology; D006046:Gold / Q000737:chemistry; D000882:Haplorhini; D008566:Membranes / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000379:methods; D045663:Quantum Dots / Q000737:chemistry
chemical_list: D015415:Biomarkers; D006046:Gold
keywords: Atmospheric electron microscopy; Correlative light and electron microscopy; Fluorescence microscopy; Nanoparticles; Quantum dots; Scanning electron microscopy